This can't be true. Pump shotguns don't jam, only semi-auto's do.
The easiest solution for you is to change ammo. If it keeps up, contact the manufacturer.
"Throughout history, it has been the inaction of those who could have acted; the indifference of those who should have known better; the silence of the voice of justice when it mattered most; that has made it possible for evil to triumph."
-Haile Selassie I